Face-to-face dies with probe pads for pre-assembly testing

ABSTRACT

In accordance with the disclosure, one or both semiconductor dies in a face-to-face arrangement may include a probe pad layer formed on a face of the die to allow the die to be individually tested prior to assembly of the dies. Thus, faulty dies may be discarded individually so they are not included in a composite semiconductor device, thereby increasing device yields. The probe pad layer also allows dies to be matched so that a composite semiconductor device achieves desired performance, which may further increase device yields. In some embodiments, the probe pads of the probe pad layer formed on the face of the die may be used to individually test the die, and may remain inactive, or inert, during operation of the composite semiconductor device.

BACKGROUND

It is sometimes not possible or practical to form a semiconductor devicefrom one integrated substrate (or semiconductor die) that includes allof the circuitry desired for the device. Thus, semiconductor deviceshave been formed from two or more semiconductor dies. Forming asemiconductor device from multiple dies may be challenging. For example,there may be hundreds to thousands of connections required to transmitsignals between chips. To achieve high speed operation, connectionresistance should be low with short path lengths to minimize inductiveand capacitive effects. Further, as semiconductor devices scale and moretransistors are integrated into a device, the power and current levelsrequired to operate the transistors may also increase—thereby makingpower delivery more challenging. Additionally, semiconductor deviceyields may be reduced, as the entire multi-die device may need to bediscarded after testing. Other challenges include arranging componentsof semiconductor dies to avoid interference between the components thatmay degrade device performance.

Conventionally, a face-to-face arrangement of semiconductor dies isassembled at a fabrication facility to form a semiconductor device. Thecomposite semiconductor device is then provided to a testing facilitywhere it is tested for proper performance. If the semiconductor devicefails testing, the entire device is discarded. For example, if eithersemiconductor die includes a critical fault or the compositesemiconductor device does not meet performance requirements the entiredevice may need to be discarded after testing, thereby reducingsemiconductor device yields.

SUMMARY

The present disclosure relates to approaches for enhancing semiconductorarrangements that include face-to-face semiconductor dies. In somerespects, one or both of the semiconductor dies may include probe padsformed over the semiconductor substrate of the die to test thesemiconductor die prior to mounting the semiconductor dies face-to-face.

Disclosed approaches provide for one or both semiconductor dies in aface-to-face arrangement including a probe pad layer formed on a face ofeach die to allow the die to be individually tested prior to assembly ofthe dies. Thus, faulty dies may be discarded individually so they arenot included in a composite semiconductor device, thereby increasingdevice yields. The probe pad layer also allows dies to be matched sothat a composite semiconductor device achieves desired performance,which may further increase device yields. In some embodiments, eachsemiconductor die may be tested (e.g., at a fabrication facilitypre-dicing), then additional interface layers (e.g., comprising bumppads and dielectric material) may be formed over the probe pad layer andused to bond the semiconductor dies in a face-to-face arrangement toform a composite semiconductor device. The composite semiconductordevice may then be tested using a different probe pad layer. In someembodiments, the probe pads of the probe pad layer formed on the face ofthe die may be used to individually test the die, and may remaininactive, or inert, during operation of the composite semiconductordevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The present systems and methods for face-to-face dies probe pads forpre-assembly testing is described in detail below with reference to theattached drawing figures, wherein:

FIG. 1A is a diagram of an example cross-section of a face-to-facearrangement of semiconductor dies, in accordance with some embodimentsof the present disclosure;

FIG. 1B is a diagram of an example cross-section of a face-to-facearrangement of semiconductor dies, in accordance with some embodimentsof the present disclosure;

FIG. 1C is a diagram of an example cross-section of a face-to-facearrangement of semiconductor dies, in accordance with some embodimentsof the present disclosure;

FIG. 2 is a diagram of an example cross-section of a semiconductorpackage that includes a face-to-face arrangement of semiconductor dies,in accordance with some embodiments of the present disclosure;

FIG. 3A is a diagram of an example cross-section of a face-to-facearrangement of semiconductor dies that includes a void for an inductor,in accordance with some embodiments of the present disclosure;

FIG. 3B is a diagram of an example cross-section of a face-to-facearrangement of semiconductor dies that includes a void for an inductor,in accordance with some embodiments of the present disclosure;

FIG. 4A is a diagram of an example cross-section of a semiconductor dieincluding probe pads for testing prior to including the semiconductordie a face-to-face arrangement of semiconductor dies, in accordance withsome embodiments of the present disclosure;

FIG. 4B is a diagram of an example cross-section of a semiconductor dieincluding additional interface layers formed over the probe pads of FIG.4A, in accordance with some embodiments of the present disclosure;

FIG. 4C is a diagram of an example top view of a testing tile structurewhich may be included in a semiconductor die, in accordance with someembodiments of the present disclosure;

FIG. 4D is a diagram of an example top view of an arrangement of testingtile structures which may be included in a semiconductor die, inaccordance with some embodiments of the present disclosure; and

FIG. 5 is a flow diagram showing a method for testing at least onesemiconductor die prior to assembly in a face-to-face arrangement withanother semiconductor die, in accordance with some embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The present disclosure relates to approaches for enhancing semiconductorarrangements that include face-to-face semiconductor dies.

The challenges in forming semiconductor devices from multiple dies hasimpacted the types of devices, configurations, and components found inmulti-die devices. Multi-die devices are often provided with diesmounted in a face-to-back arrangement. In particular, single dies areoften front to back so a stacked arrangement may naturally follow fromthis configuration by stacking similarly arranged dies. However, using aface-to-back arrangement may require all signals to be communicatedbetween the dies using Through Silicon Vias (TSVs) that extend throughthe entire bottom die. The size of the TSVs results in a lower densityof interconnects between the dies, thereby limiting performance anddesign flexibility. Further, the dies may be connected using microbumpsthat require an underfill that compromises the thermal performance ofthe composite structure.

A face-to-face arrangement may allow for significantly higher density ofinterconnects between the dies by forming interconnects from bump padmetal, but is a less natural arrangement and introduces significantchallenges from a design and fabrication standpoint. For example,semiconductor devices have not used a face-to-face arrangement ofsemiconductor dies that each include a graphics processing unit (GPU)due to these challenges. In such configurations, many signals may beneeded for the GPUs to communicate between chips, the GPU in asemiconductor die may require more power than can practically bedelivered, and die sizes may be large enough that yields areprohibitively low. Further, it may be desirable to form one or moreinductors over the semiconductor substrate of one or both dies, such asfor high speed clock operation and/or power filtering, but interferencefrom an adjacent die may degrade an inductor's performance. As such,these types of inductors have not been used in semiconductor deviceswith face-to-face die arrangements.

In contrast to conventional approaches, one or both semiconductor diesin a face-to-face arrangement may include a probe pad layer formed on aface of the die to allow the die to be individually tested prior toassembly of the dies. Thus, faulty dies may be discarded individually sothey are not included in a composite semiconductor device, therebyincreasing device yields. The probe pad layer also allows dies to bematched so that a composite semiconductor device achieves desiredperformance, which may further increase device yields. For example,where each die includes a number of processing cores, testing may beused to bypass faulty cores and select dies so that the compositesemiconductor device collectively includes a threshold number of activecores. In some embodiments, each semiconductor die may be tested (e.g.,at a fabrication facility pre-dicing), then additional interface layers(e.g., comprising bump pads and dielectric material) may be formed overthe probe pad layer and used to bond the semiconductor dies in aface-to-face arrangement to form a composite semiconductor device. Thecomposite semiconductor device may then be tested using a differentprobe pad layer. In some embodiments, the probe pads of the probe padlayer formed on the face of the die may be used to individually test thedie, and may remain inactive during operation of the compositesemiconductor device.

In further contrast to conventional approaches, disclosed approachesprovide for forming an inductor over the semiconductor substrate of oneor both dies in a face-to-face die arrangement while reducing theparasitic capacitance between the inductor and the adjacent die. Indisclosed embodiments, a semiconductor device may include a void (e.g.,an air gap) between the inductor and the adjacent die to reduce theparasitic capacitance between the inductor and the adjacent die. Thevoid may be formed in the die that includes the inductor and/or theadjacent die. In some respects, the void may be etched in interfacelayers (e.g., comprising bump pads and dielectric material) between thesemiconductor dies, and may extend along the length of the inductor.

Also in contrast to conventional approaches, disclosed approachesprovide for a TSV of a first semiconductor die that extends from asemiconductor substrate of the first semiconductor die on an insulatedpath through at least one metallization layer of the die to electricallyand mechanically connect to a different metallization layer to supplypower to the second semiconductor die. By extending the TSV, resistanceat higher layers (layers further from source) may be reduced allowingfor enhanced power delivery to the second semiconductor die. Resistancemay further be reduced by allowing for the TSV to electrically andmechanically connect to a thicker metallization layer than wouldotherwise be possible. In an example and non-limiting embodiment, thethicker metallization layer may have a highest thickness of all of themetallization layers (e.g., a topmost or near-topmost metallizationlayer of a metallization stack). Also, in some embodiments, themetallization layer that the TSV electrically and mechanically connectsto is capable of supplying power to both semiconductor dies. The firstsemiconductor die may be a top die or a bottom die in a face-to-facearrangement. Further, where additional dies are included in a die stack,any number of the dies may include one or more TSVs that extend from asemiconductor substrate of the die on an insulated path through at leastone metallization layer of the die to electrically and mechanicallyconnect to a different metallization layer to supply power to anotherdie.

With reference to FIG. 1A, FIG. 1A is a diagram of an examplecross-section of a face-to-face arrangement 102 of semiconductor dies,in accordance with some embodiments of the present disclosure. It shouldbe understood that this and other arrangements described herein are setforth only as examples. Other arrangements and elements may be used inaddition to or instead of those shown, and some elements may be omittedaltogether. Further, the drawings and illustrations in the presentapplication are not necessarily to scale, and do not necessarilyindicate actual relative dimensions.

The face-to-face arrangement 102 includes at least a semiconductor die104 and a semiconductor die 106. The semiconductor die 106 may include asemiconductor substrate 108, a metallization region 110, an interfaceregion 112, and an interface region 114. The semiconductor die 104 mayinclude an interface region 124.

As an overview, the semiconductor die 106 may include any number ofThrough Silicon Vias (TSVs), such as a TSV 120 and a TSV 122. While theface-to-face arrangement is described with respect to TSVs, such as theTSV 120 and the TSV 122, the TSVs may more generally be referred to asThrough Wafer Vias (TWVs) or Through Chip Vias (TCVs), as someembodiments may use a non-silicon material. One or more of the TSVs,such as the TSV 120 may extend from the semiconductor substrate 108 ofthe semiconductor die 106 through at least one metallization layer ofthe metallization region 110 to a metallization layer of themetallization region 110 to supply power to the semiconductor die 104through the metallization layer, the interface region 112 of thesemiconductor die 106, and the interface region 124 of the semiconductordie 104. By extending the TSV through at least one metallization layerof the metallization region 110, power distribution to the semiconductordie 104 may be enhanced.

The semiconductor substrate 108 includes semiconductor material, such assingle-crystal semiconductor material. In the present example, thesemiconductor substrate 108 is a silicon substrate and more particularlyis monocrystalline silicon. However, the semiconductor substrate 108 maycomprise any suitable semiconductor material(s), such as a group IVsemiconductor material or group III-V semiconductor material.

Group IV refers to a semiconductor that includes at least one group IVelement such as silicon (Si), germanium (Ge), and carbon (C), and mayalso include compound semiconductors such as silicon germanium (SiGe)and silicon carbide (SiC), for example. Group IV also refers tosemiconductor materials which include more than one layer of group IVelements, or doping of group IV elements to produce strained group IVmaterials, and may also include group IV based composite substrates suchas single-crystal or polycrystalline SiC on silicon, silicon oninsulator (SOI), separation by implantation of oxygen (SIMOX) processsubstrates, and silicon on sapphire (SOS), for example.

Group III-V refers to a compound semiconductor including at least onegroup III element and at least one group V element. By way of example, agroup III-V semiconductor may take the form of a III-Nitridesemiconductor. III-Nitride or III-N refers to a compound semiconductorthat includes nitrogen and at least one group III element such asaluminum (Al), gallium (Ga), indium (In), and boron (B), and includingbut not limited to any of its alloys, such as aluminum gallium nitride(AlxGa(1−x)N), indium gallium nitride (InyGa(1−y)N), aluminum indiumgallium nitride (AlxInyGa(1−x−y)N), gallium arsenide phosphide nitride(GaAsaPbN(1−a−b)), aluminum indium gallium arsenide phosphide nitride(AlxInyGa(1−x−y)AsaPbN(1−a−b)), for example. III-N also refers generallyto any polarity including but not limited to Ga-polar, N-polar,semi-polar, or non-polar crystal orientations. A III-N material may alsoinclude either the Wurtzitic, Zincblende, or mixed polytypes, and mayinclude single-crystal, monocrystalline, polycrystalline, or amorphousstructures.

One or more electronic circuits may be formed, at least partially withinthe semiconductor substrate 108. An electronic circuit may include oneor more transistors, such as a transistor 126. In the present example,the electronic circuit may form at least a portion of a GPU. Forexample, the semiconductor die 106 may be a GPU die. However, varioustypes and configurations of electronic circuits are contemplated asbeing within the score of the present disclosure. As some examples, thesemiconductor substrate 108 may include one or more circuit componentsof a processing unit, a Central Processing Unit (CPU), a singletransistor (e.g., a power transistor), a logic circuit, a power circuit,a System on Chip (SoC), and a transmitter and/or receiver. Where thesemiconductor substrate 108 includes a processing unit, the processingunit may include any number of cores. For example, where the processingunit is a GPU, the GPU may include multiple Streaming Multiprocessors(SMs) and each Streaming Multiprocessor may include a number cores.

The metallization region 110 may be formed on the semiconductorsubstrate 108 and comprise any number of metallization layers andinterlayer dielectric layers. Of the metallization layers shown in FIG.1A, a metallization layer 130, a metallization layer 132, and ametallization layer 134 are individually labeled. Also, of theinterlayer dielectric layers shown in FIG. 1A, an interlayer dielectriclayer 136 and an interlayer dielectric layer 138 are individuallylabeled. The metallization layers of the metallization region 110 mayinterconnect the various circuit components and/or electronic circuitsof the semiconductor die 106 and/or the semiconductor die 104. Thenumber of the metallization layers included in the metallization region110 and the thickness of those layers may vary depending on the designof the semiconductor die 106 and the circuit components and electroniccircuits included in the semiconductor die 106. Generally, the thicknessof the metallization layers may remain constant, or may increase towarda face 140A of the semiconductor die 106 and a face 140B of thesemiconductor die 104. As a specific example, the metallization region110 may include sixteen metallization layers. The bottom sixmetallization layers (e.g., including the metallization layer 130) mayhave the same thickness, followed by four metallization layers that are(as a non-limiting example) three to four times thicker than the bottommetallization layers, followed by two metallization layers (e.g., themetallization layers 132 and 134) that are (for example and withoutlimitation) ten times thicker than the bottom metallization layers.

In various examples, different metallization layers may be used fordifferent purposes, which may depend on the thickness of themetallization layers. The density of routing which may be implementedusing a metallization layer may decrease as the thickness of ametallization layer increases. However, the resistivity of ametallization layer may also decrease as the thickness of ametallization layer increases. Thus, in some examples, thickermetallization layers, such as the metallization layers 132 and 134 maybe configured for power distribution and/or global clock distribution.Thinner metallization layers, such as the metallization layer 130 may beconfigured for local signal routing, such as to connect localtransistors (e.g., to the transistor 126). Other metallization layers(e.g., with a thickness between the metallization layer 130 and themetallization layers 132 and 134) may be configured for bussing (e.g.,between an electronic circuit comprising the transistor 126 and anelectronic circuit comprising a transistor 142), lower level clockdistribution, and/or power routing.

Face-to-Face Dies with Enhanced Power Delivery using TSVs

As described herein, one or more TSVs, such as the TSV 122 and/or theTSV 120 may extend from the semiconductor substrate 108 of thesemiconductor die 106 on an insulated path through at least onemetallization layer of the metallization region 110 to electrically andmechanically connect to a different metallization layer(s) of themetallization region 110 to supply power to the semiconductor die 104,to the different metallization layer(s), and to the components connectedto the different metallization layer(s). In the example shown, the TSV120 extends through the metallization layer 130 and each metallizationlayer below the metallization layer 132 in the metallization region 110to contact the metallization layer 132. However, in other examples a TSVmay extend through any number of metallization layers to contact anymetallization layer of the metallization region 110. For example, wherethe metallization region 110 includes two metallization layers, the TSVmay extend through the bottom metallization layer to contact the topmetallization layer. Also, in the example shown, rather than contactingthe metallization layer 132, the TSV may contact the metallization layer134 or any other metallization layer above the metallization layer 130.

By extending the TSV through at least one metallization layer of themetallization region 110, power distribution to the semiconductor die104 may be enhanced. For example, this may reduce the resistance of thepower supply path to the semiconductor die 104, as a TSV typically haslow resistance. The power supply path may run from the interface region114 of the semiconductor die 106 to the TSV 120, through themetallization layer 132 (e.g., a metallization segment 146), throughvias in the interlayer dielectric layer 136, through the metallizationlayer 134 (e.g., a metallization segment 148), and through the interfaceregion 112 to the interface region 124 of the semiconductor die 104.Resistance may further be reduced by allowing for the TSV to connect toa thicker metallization layer than would otherwise be possible. Forexample, the metallization layer 130 may be the thinnest and most highlyresistive of the metallization layers in the metallization region 110,and may be bypassed by extending the TSV 120 through the metallizationlayer 130.

The number of metallization layers in the metallization region 110 thata TSV is extended through and the thickness of the metallization layerthat the TSV contacts may vary depending on the design of theface-to-face arrangement 102 and the circuit components and electroniccircuits included in the face-to-face arrangement 102. For example,these factors may vary depending on the routing and layout requirementsof the face-to-face arrangement 102, as extending a TSV may introducerouting blockage in the metallization region 110. Also, these factorsmay vary depending on the power distribution requirements of theface-to-face arrangement 102. In the example shown, the TSV 120 isconfigured to supply power to circuit components in both thesemiconductor die 104 and the semiconductor die 106. For example, fromthe metallization layer 132, power may be distributed to circuitcomponents such as the transistor(s) 126 through a routing path 144 inthe metallization region 110 to reach the semiconductor substrate 108.The routing path 144 includes metallization arranged in a column, butthis arrangement may vary.

In the present example, the semiconductor die 104 and the semiconductordie 106 have substantially the same power distribution requirements. Forexample, the semiconductor die 104 and the semiconductor die 106 mayinclude the same electronic circuitry. Thus, the TSV 120 is configuredto deliver substantially the same power to the semiconductor die 104 andthe semiconductor die 106. However, the TSV 120 may in other examples beconfigured to deliver more power to the semiconductor die 104 than thesemiconductor die 106 or more power to semiconductor die 106 than thesemiconductor die 104. In some embodiments, the TSV 120 may beconfigured to deliver power to the semiconductor die 104, but not to thesemiconductor die 106 or not to a circuit component in the semiconductorsubstrate 108 of the semiconductor die 106. Also, while the TSV 120 andthe TSV 122 both contact the same metallization layer in the exampleshown, different TSVs within the semiconductor die 106 may extendthrough a different number of metallization layers to contact differentmetallization layers.

In various embodiments, the interface region 112 of the semiconductordie 106 may be formed on the metallization region 110 and mayelectrically and mechanically couple the semiconductor die 106 to thesemiconductor die 104. For example, the semiconductor die 104 may bemounted face-to-face with the semiconductor die 106 to form anelectrical and mechanical interface 150 at the interface region 112 ofthe semiconductor die 106 and the interface region 124 of thesemiconductor die 104.

Various techniques may be used to form the interface region 112 of thesemiconductor die 106 and the interface region 124 of the semiconductordie 104 so as to provide the electrical and mechanical interface 150.The interface region 112 and the interface region 114 may vary dependingon various factors, such as the desired characteristics for theelectrical and mechanical interface 150. As an example, the interfaceregion 112 and the interface region 114 may use a different techniqueand/or comprise different materials when only power is to be transferredacross the electrical and mechanical interface 150, as opposed to asignal(s) and power. FIG. 1B shows an example of the interface region112 and the interface region 114 along with an example of thesemiconductor die 104.

With reference to FIG. 1B, FIG. 1B is a diagram of an examplecross-section of a face-to-face arrangement 102 of semiconductor dies,in accordance with some embodiments of the present disclosure. In theexample of FIG. 1B, the interface region 112 and the interface region114 each include bonding dielectric (e.g., bonding oxide) and inter-dieinterface pads (e.g., formed from one or more bump pad layers and/orinter-die interface pad layers) that forms the electrical and mechanicalinterface 150. By way of example, the bonding dielectric may include abonding dielectric layer 152 (e.g., a bonding oxide layer). Also by wayof example, inter-die interface pads may include bump pads in thebonding dielectric layer 152, of which bump pads 154, 156, and 158 areindividually labeled. The bump pads 154 and 156 may be used to supplypower to the semiconductor die 104 and the interface region 112. Bumppad vias, such as a bump pad via 160, may be used to connect the bumppads 154 and 156 to the metallization layer 134. The bump pad 158 may,for example, be used to communicate a signal between the semiconductordie 104 and the semiconductor die 106. Any number of bump pads may beused to facilitate the exchange of power and/or signals between thesemiconductor die 104 and the semiconductor die 106.

The interface region 124 of the semiconductor die 104 may be similar tothe interface region 112 of the semiconductor die 106, with similarlydepicted elements representing corresponding features in the interfaceregion 112. However, in other examples, the interface region 124 mayinclude different elements than the interface region 112. As indicatedin FIG. 1B, the interface region 124 of the semiconductor die 104 mayreceive power from the TSV 120, which may be delivered to an electricalcircuit(s) comprising one or more circuit components, such as atransistor 162 formed at least partially in a semiconductor substrate164 of the semiconductor die 104 (e.g., using one more metallizationlayers in a metallization region 166).

The description of the semiconductor substrate 108 and the semiconductordie 106 may apply to the semiconductor substrate 164 and thesemiconductor die 104 and is therefore not repeated. However, theexamples may be mixed and matched such that the semiconductor substrate108 may comprise similar or different material than the semiconductorsubstrate 164. Similarly, the description of the metallization region110 and the semiconductor die 106 may apply to metallization region 166and the semiconductor die 104 and is therefore not repeated (e.g., thesame or a different number of layers may be included of similar ordifferent thicknesses). However, in some embodiments the semiconductordie 104 does not include the metallization layers 166 and/or may includea single metallization layer.

In the example of FIG. 1B, the semiconductor die 106 and thesemiconductor die 104 may be fabricated using the same mask set and thesame base wafer material. This allows for reduced cost by avoiding anadditional mask set. Further, device yields may be increased, forexample, as fabrication can be tailored to a single design.

As an example of fabricating the face-to-face arrangement 102, a wafercomprising the semiconductor substrate 108 may be processed to fabricatethe semiconductor die 106 comprising the metallization region 110. Theinterface region 112 may be formed on the metallization region 110 andthe wafer may be diced, or singulated, to form individual dies includingthe semiconductor die 106.

Also, a different wafer comprising the semiconductor substrate 164 maybe processed to fabricate the semiconductor die 104 comprising themetallization region 166. This processing may use the same mask set usedfor the semiconductor die 106 (or a different mask set in someembodiments). The interface region 124 may be formed on themetallization region 166. This processing may use the same mask set asused for the interface region 112 of the semiconductor die 106, or adifferent mask set. A pick and place machine may be used to mount thesingulated dies formed from the semiconductor substrate 108 with therespective unsingulated dies formed from the semiconductor substrate 164in face-to-face arrangements. This may form the face-to-face arrangement102. The singulated dies may then be thinned and the TSVs, such as theTSV 120 and the TSV 122 may be revealed. Subsequently, the interfaceregion 114 may be formed and the face-to-face arrangements may besingulated.

In some embodiments, the semiconductor die 104 is bilaterallysymmetrical to the semiconductor die 106 (and/or the mask set(s) used toform the semiconductor dies 104 and 106), as indicated by symmetry line170. When mounting the semiconductor die 106 and the semiconductor die106 in the face-to-face arrangement 102, the semiconductor die 106 maybe rotated and flipped around the symmetry line 170 (like book pages) toalign symmetrically-positioned contact points on the interface regions112 and 124. Other types of symmetry are covered by the disclosure, suchas quadrilateral symmetry and/or rotational symmetry. For example, thesemiconductor die 106 may be rotated 180 degrees and flipped around thesymmetry line 170 to align symmetrical contact points on the interfaceregions 112 and 124.

Where the semiconductor dies (and/or masks and/or surface contacts onthe face of the dies) are symmetrical, in some embodiments, one or morestructures in the semiconductor die 106 may have a correspondingstructure in the semiconductor die 104 that is configured for adifferent purpose or function than in the semiconductor die 106. Forexample, FIG. 1B shows a structure 176 (an electrically conductivestructure) of the semiconductor die 106 (including at least the TSVs 120and 122, connected metallization segments, such as the metallizationsegments 146 and 148, and connected microvias, such as those of therouting path 144), which may correspond to a structure 178 of thesemiconductor die 104. In the semiconductor die 106, the structure 176may be configured to supply power to the semiconductor die 104. In someembodiments, the structure 176 for purposes of this description does notrefer to connected components (e.g., the bump pad via 160 and the bumppads 154 and 156) in the interface region 112, while in others it may.For example, the interface region 124 and the interface region 112 maynot include analogous and/or duplicate structure. In the semiconductordie 104, the structure 178 may be configured to supply power to anelectronic circuit in the semiconductor substrate 164 (e.g., using bumppad vias in the interface region 112, such as the bump pad via 160 andbump pads, such as the bump pads 154 and 156), may remain unused orinactive (e.g., electrically inert) as a vestigial structure (e.g., notused to carry signals and/or power), or may be configured to perform adifferent function, such as to supply power to a semiconductor die(e.g., via one or more portions of the structure 178 that correspond tothe TSVs 120 and/or 122) and/or electrical component on thesemiconductor die 104 (e.g., via the interface region 124 which may beconfigured similar to or different than the interface region 112 withrespect to bump pad vias and bump pads) in embodiments that includethose additional elements.

FIG. 1B also shows a structure 182 (e.g. including connectedmetallization segments and microvias) of the semiconductor die 104,which may correspond to a structure 184 of the semiconductor die 106.Similar to the structures 176 and 178, the structures 182 and 184 may bean example of one or more corresponding structures that are configuredfor a different purpose or function for the semiconductor dies 104 and106. Also similar to the structures 176 and 178, in some embodiments,the structures 182 and 184 for purposes of this description do not referto connected components (e.g., bump pad vias and bump pads in theinterface regions 112 and 124, while in others they may. As indicated bythe region 172, the structures 178 and 182 may be configured to connectand/or align across the semiconductor dies 104 and 106. A similarconfiguration is shown for a region 174. In some embodiments, suchregions may be vestigial and may not be used for characterization of theface-to-face arrangement 102.

While the structure 176 and the structure 178 are substantially similarin FIG. 1B, the corresponding structures may be different from oneanother. For example, even where the same masks are used to form thestructures in the semiconductor dies 104 and 106, the correspondingstructures may be different. As an example, TSVs may not be formed inthe semiconductor die 104, the region 172, and/or the region 174.Referring now to FIG. 1C, FIG. 1C is a diagram of an examplecross-section of a face-to-face arrangement 102 of semiconductor dies,in accordance with some embodiments of the present disclosure. In thisexample, TSVs are not formed in the semiconductor die 104. Thus, thestructure 178 may not include TSVs that correspond to the TSVs 120 and122 of the structure 176, but may otherwise be similar. Additionally oralternatively, as described, portions of the structure 178 in theinterface region 124 may be different than portions of the structure 176in the interface region 112 (or no portion of the structure 178 may bein the interface region 124).

FIG. 1B also shows an example of the interface region 114 of thesemiconductor die 106. In the example of FIG. 1B, the interface region114 includes microbumps, such as a microbump 190A and a microbump 190B,which may serve as power and/or Input/Output (IO) terminals of theface-to-face arrangement 102. Thus, the interface region 114 maycomprise a communications and/or power interface to the face-to-facearrangement 102. For example, the microbump 190A and the microbump 190Bmay be configured as power supply terminals of the face-to-facearrangement 102. The interface region 114 may further include one ormore backside redistribution layers, such as a backside redistributionlayer 194. The interface region 114 may vary depending on such factorsas the packaging used to house the face-to-face arrangement 102,fabrication constraints or technologies, whether the semiconductor die104 or the semiconductor die 104 is the top die or the bottom die in theface-to-face arrangement 102, and/or whether there are additionalsemiconductor dies (e.g., in a face-to-face arrangement) and/orelectrical components stacked on the face-to-face arrangement 102, etc.

Now referring to FIG. 2 , FIG. 2 is a diagram of an examplecross-section of a semiconductor package 200 that includes aface-to-face arrangement 102 of semiconductor dies, in accordance withsome embodiments of the present disclosure. In the semiconductor package200, the face-to-face arrangement 102 is electrically and mechanicallycoupled to an interposer 202 by microbumps 290, which may include themicrobumps 190A and 190B of FIG. 1B. The interposer 202 may beelectrically and mechanically coupled to a package substrate 204 bysolder bumps 210, which may be C4 bumps. Also, the package substrate 204includes solder balls 212, which may serve as terminals or pins of thesemiconductor package 200. The semiconductor package 200 may includeother elements not shown, such as encapsulant and additional dies and/orelectrical components. One or more of the solder balls 212 may be apackage power supply terminal of the semiconductor package 200, and maybe electrically connected to the interface region 114 of thesemiconductor die 106, such as by the microbump 190A and the microbump190B. One or more of the solder balls 212 may also be a package signal,or IO terminal of the semiconductor package 200, and may be electricallyconnected to the interface region 114 of the semiconductor die 106, suchas by one or more of the microbumps 290. The semiconductor package 200is provided as one suitable example of a semiconductor package, butother packaging types and technologies may be used in disclosedembodiments.

Face-to-Face Dies with a Void for Enhanced Inductor Performance

Aspects of the disclosed approaches provide for forming an inductor overa semiconductor substrate of one or both dies in a face-to-face diearrangement while reducing the parasitic capacitance between theinductor and the adjacent die. In disclosed embodiments, thesemiconductor device may include a void (e.g., an air gap) between theinductor and the adjacent die to reduce the parasitic capacitancebetween the inductor and the adjacent die. The void may be etched ininterface layers (e.g., comprising inter-die interface pads anddielectric material) between the semiconductor dies, and may extendalong the length of the inductor. FIG. 3A shows one such example of asuitable face-to-face arrangement of semiconductor dies, but manydifferent variations are within the score of the present disclosure.

Now referring to FIG. 3A, FIG. 3A is a diagram of an examplecross-section of a face-to-face arrangement 302 of semiconductor diesthat includes a void for an inductor, in accordance with someembodiments of the present disclosure.

The face-to-face arrangement 302 may be the same as or different thanthe face-to-face arrangement 102 of FIGS. 1A and/or 1B. In theface-to-face arrangement 302, one or more inductors may be formed overthe semiconductor substrate 108 of the semiconductor die 106. Examplesin FIG. 3A include an inductor 304 and an inductor 306. The inductors304 and 306 may be included in the face-to-face arrangement 302 for, asexamples, high speed clock operation and/or power filtering (e.g., ofpower received from a power supply terminal of the face-to-facearrangement 302). In embodiments where the inductor 304 and/or theinductor 306 are used for clocking, the inductor may connect tophase-locked loop (PLL) circuitry (to generate a clock signal) and maynot include a connection to a TSV (or a power supply path) and/or tooutside of the semiconductor package 200.

In the example shown, the inductors 304 and 306 are formed in theinterface region 112. In other examples, one or more inductors may inaddition or instead be formed in a different region, such as themetallization region 110. As shown, the face-to-face arrangement 302includes a void 308 between the inductor 304 and the semiconductor die104 and a void 310 between the inductor 306 and the semiconductor die104. The voids 308 and 310 may be an air gap configured to reduce theparasitic capacitance between the inductors 304 and 306 and thesemiconductor die 104. The voids 308 and 310 may extend along the lengthof the inductors 304 and 306 respectively along a direction parallel tothe face 140A of the semiconductor die 106. The voids 308 and 310 mayalso extend from a distal plane on the face 140A of the semiconductordie 106 to the inductors 304 and 306 respectively. For example, thevoids 308 and 310 may be formed in the surface of the interface region112 by etching the voids 308 and 310 in the bonding dielectric layer152. In other examples, the voids may be etched in additional ordifferent portions of the interface region 112. Also in someembodiments, the voids 308 and 310 may be formed at least partially onthe semiconductor die 104. In some examples, the inductor 304 or 306 isat least partially on a distal plane on the face 140A of thesemiconductor die 106, and the void 308 or 310 is formed on a distalplane on the face 140B of the semiconductor die 104 rather than on thesemiconductor die 106 (e.g., by etching the void(s) in the interfaceregion 124).

The semiconductor die 106 may also include a voided region between theinductor and the backside of the semiconductor die 106 to avoidparasitic capacitance between the inductor and elements of thesemiconductor die 106. For example, a voided region 312 is shown, whichmay extend to the backside of the semiconductor die 106. The voidedregion 312 may also extend along the length of the inductor 304, similarto the void 308. The voided region 312 is configured to be floating.Thus, while conductive material, such as metallization may be in thevoided region 312 (e.g., as fill material to satisfy design rules), theconductive material is floating (e.g., comprising non-signal carryinglayers) so as to avoid parasitic capacitance with the inductor 304. FIG.3B is used to describe additional examples of the face-to-facearrangement 302.

FIG. 3B is a diagram of an example cross-section of the face-to-facearrangement 302 of semiconductor dies that includes a void for aninductor, in accordance with some embodiments of the present disclosure.As shown in FIG. 3B, the semiconductor die 104 may also include a voidedregion 314 for the inductor 304, which may be similar to the voidedregion 312. FIG. 3B also shows an example where the semiconductor die104 includes an inductor 316, a void 318, and a voided region 320, whichmay be similar to or different than the inductor 304, the void 308, andthe voided region 312, respectively. Further, the semiconductor die 106includes a voided region 322, which may be similar to the voided region314. Thus, one or both of the semiconductor dies 104 or 106 may includean inductor and corresponding void. Further, the inductor and void maybe formed in different layers in each semiconductor die. Also, invarious embodiments, an inductor (e.g., the inductor 304, 306, and/or316) may optionally be formed in one semiconductor die and connected toelectronic circuitry (e.g., to provide a clock, etc.) in the other diein addition to or instead of the semiconductor die. While like FIG. 3B,FIG. 1B shows the inductors and voids, the face-to-face arrangement 102may be provided without one or more of those elements. Also, while likeFIG. 1B, FIG. 3B shows TSVs that extend through at least onemetallization layer, the face-to-face arrangement 302 may be providedwithout one or more of those elements.

Face-to-Face Dies with Probe Pads for Pre-Assembly Testing

Aspects of the disclosed approaches provide for one or bothsemiconductor dies in a face-to-face arrangement including at least oneprobe pad layer formed on a face of the die to allow the die to beindividually tested prior to assembly of the dies. Thus, faulty dies maybe discarded individually so they are not included in a compositesemiconductor device, or dies may be better matched, thereby increasingdevice yields. In some embodiments, a semiconductor die may be tested(e.g., at a fabrication facility pre-dicing), then additional interfacelayers (e.g., comprising inter-die interface pads and dielectricmaterial) may be formed over the probe pad layer and used to bond thesemiconductor dies in a face-to-face arrangement to form a compositesemiconductor device. FIGS. 4A and 4B show one such example used todescribe testing, then forming additional interface layers over asemiconductor die prior to including the semiconductor die aface-to-face arrangement of semiconductor dies, but many differentvariations are within the score of the present disclosure.

FIG. 4A is a diagram of an example cross-section of the semiconductordie 106 including probe pads for testing prior to including thesemiconductor die 106 in the face-to-face arrangement 102 ofsemiconductor dies, in accordance with some embodiments of the presentdisclosure. The semiconductor die 106 of FIGS. 4A and 4B may correspondto the semiconductor die 106 during fabrication and pre-assembly intothe face-to-face arrangement 102.

The interface region 112 of FIG. 4A is formed on a die region 410 on theface 140B of the semiconductor die 106. The die region 410 is showngenerically to indicate the broad applicability of the approachesdescribed with respect to FIGS. 4A and 4B, but may in some embodimentsinclude the metallization region 110 and the semiconductor substrate108. In some embodiments, the interface region 114 is not yet formed onthe semiconductor die 106.

The interface region 112 of FIG. 4A includes a plurality of probe pads,of which probe pads 406 and 408 are shown. The probe pads may comprise,for example, aluminum probe pads formed from a probe pad layer(s). Inembodiments where the interface region 112 includes at least oneinductor, such as the inductor 304 or the inductor 306, one or more ofthe inductors may also be formed from the probe pad layer(s), as shown,and/or from a different layer(s). The probe pads may be configured totest one or more electronic circuits in the semiconductor die 106, suchas an electronic circuit comprising the transistor 126 and/or 142. Forexample, the probe pads may be electrically connected to the electroniccircuit(s) by the metallization region 110 for testing. As an example,the semiconductor die 106 may be tested prior to dicing, along withother similar semiconductor dies on the wafer. Further, this testing mayoccur at the fabrication facility used to fabricate the wafer.

Subsequent to testing the wafer comprising the semiconductor die 106,the wafer may undergo further processing (e.g., at the fabricationfacility) to produce the semiconductor die 106 of FIG. 4B. FIG. 4B is adiagram of an example cross-section of the semiconductor die 106including additional interface layers formed over the probe pads of FIG.4A, in accordance with some embodiments of the present disclosure. Theadditional processing may include forming one or more bonding dielectriclayers, such as the bonding dielectric layer 152 over the probe padlayer and/or probe pads. Additionally, any number of inter-die interfacepads, such as the bump pads 154, 156, or 158 may be formed in thebonding dielectric layer 152. Further, in embodiments that include oneor more inductors, voids—such as the voids 308 or 310—may be formed inthe bonding dielectric layer 152. The semiconductor die 106 may then bemounted to the semiconductor die 104 in the face-to-face arrangement 102using the bonding dielectric layer 152.

In the face-to-face arrangement 102, the probe pads of the probe padlayer may be insulated from the semiconductor die 104 and may remaininactive during operation of the semiconductor die 106. Thus, the probepads may only be operated for testing of the semiconductor die 106pre-assembly, but may remain as vestiges and electrically inert in theface-to-face arrangement 102. In other examples, the probe pads may beconfigured or reconfigured for operation of the semiconductor die 106and/or the semiconductor die 104 in the face-to-face arrangement 102.

While FIGS. 4A and 4B are described with respect to the semiconductordie 106, FIGS. 4A and 4B may also apply to the semiconductor die 104.For example, the interface region 124 of the semiconductor die 104 maybe formed similar to the interface region 112, including testing thesemiconductor die 104 at the fabrication facility, then performingadditional processing to arrive at the configuration of FIG. 4B.However, in some embodiments the semiconductor die 104 may include probepads in the interface region 124 while the semiconductor die 106 doesnot include probe pads in the interface region 112, or the semiconductordie 106 may include probe pads in the interface region 112 while thesemiconductor die 104 does not include probe pads in the interfaceregion 124.

To form the face-to-face arrangement 102, the wafer comprising thesemiconductor die 106 may be singulated and a pick and place machine maybe used to mount the singulated dies formed from the semiconductorsubstrate 108 with the respective unsingulated dies formed from thesemiconductor substrate 164 in face-to-face arrangements including theface-to-face arrangement 102. In embodiments where the semiconductorsubstrate includes TSVs, the singulated dies may then be thinned and theTSVs, such as the TSV 120 and the TSV 122 may be revealed. Subsequently,the interface region 114 may be formed and the face-to-face arrangementsmay be singulated. The interface region 114 may be used to test thesemiconductor die 104 and/or the semiconductor die 106, such as bytesting a composite semiconductor device (e.g., a composite logiccircuit) formed from the semiconductor die 104 and the semiconductor die106 (e.g., in the semiconductor package 200 and/or prior to inclusion ina semiconductor package). This testing may occur at a testing facilityseparate from the fabrication facility and may use microbumps in theinterface region 114, such as the microbump 190A and/or the microbump190B (e.g. power and signal terminals used during regular operation)and/or may use backside probe pads in the interface region 114, such asa probe pad 192A and/or a probe pad 192B formed in a backside probe padlayer (e.g. prior to formation of the microbumps). As the semiconductordies may be tested pre-assembly, faulty dies may be discarded so theyare not included in a face-to-face arrangement and/or dies may bematched, thereby increasing device yields.

Referring now to FIG. 4C, FIG. 4C is a diagram of an example top view ofa testing tile structure 416 which may be included in semiconductor die106, in accordance with some embodiments of the present disclosure. Thesemiconductor die 106 may include any number of testing tile structures,which may appear similar to the testing tile structure 416 and may bearranged in a grid-like arrangement. The testing tile structure 416includes the probe pads 406 and 408, as well as a probe pad 418 and aprobe pad 420. In other embodiments the testing tile structure 416 mayinclude a different number of probe pads. During testing, pins oftesting hardware may electrically and mechanically interface with thetesting tile structure 416 at the probe pads. As an example, the probepads may each be approximately 50×50 microns, and larger than theinter-die interface pads (e.g., the bump pads 154, 156, and 158).

The probe pad 406 may be configured as a power supply terminal of thetesting tile structure 416 and the probe pad 408 may be configured as aground pad of the testing tile structure 416 during the testing.Further, the probe pads 418 and 420 may be configured as respectivesignal terminals of the testing tile structure 416 during the testing.While the testing tile structure 416 includes two signal terminals inthe example shown, the testing tile structure 416 may be used to testmore than two signals in the semiconductor die 106 by serializing thesignals. Each probe pad may be electrically connected to a respectiveportion of a redistribution layer, as shown in FIG. 4C. In the exampleshown, the portions of the redistribution layer include interdigitatedfingers, or rows. Each node on a finger may be coupled to an underlyingvia and routed to a corresponding circuit element(s) in thesemiconductor substrate 108 (e.g., the transistor 126). While thetesting tile structure 416 is shown, embodiments of the presentdisclosure may not use a testing tile structure for testing. Also, thesemiconductor die 104 may include a similar or different testingstructure.

Referring now to FIG. 4D, FIG. 4D is a diagram of an example top view ofan arrangement 430 of testing tile structures 416 which may be includedin the semiconductor die 106, in accordance with some embodiments of thepresent disclosure. While only eight testing tile structures 416 areshown in FIG. 4D, the semiconductor die 106 may include, as an example,thousands of testing tile structures 416. In a specific and non-limitingexample, the semiconductor die 106 may by approximately 20 millimetersby 20 millimeters and a testing tile structure 416 may be approximately200 micrometers by 200 micrometers. Thus, as many as 10,000 testing tilestructures 416 may fit in the arrangement 430. However, in the presentexample, the region 432 does not include a testing tile structure 416.Instead, the region 432 may include one or more other testing tilestructures and/or testing structures, or may not include any probe padsor testing structures. In some examples, the region 432 corresponds to acrossbar configured for inter-die communication of signals between thesemiconductor die 104 and the semiconductor die 106 in the face-to-facearrangement 102. The crossbar may be used to communicatively couple aprocessing unit in the semiconductor die 104 with a processing unit inthe semiconductor die 106.

Although FIGS. 4C and 4D are described with respect to the semiconductordie 106, FIGS. 4C and 4D may also apply to the semiconductor die 104.For example, the semiconductor die 104 may include similar or differenttesting structures (e.g., tiles) as the semiconductor die 104 in asimilar or different arrangement.

In embodiments where the semiconductor die 106 comprises a processingunit, the testing tile structures 416 may each correspond to one or morerespective processing cores of the processing unit (e.g., thatunderlines the testing tile structure 416). Using the testing tilestructures 416, each processing core(s) may be individually tested. Forexample, where the semiconductor die 106 comprises a GPU, each testingtile structure 416 may correspond to a respective SM and may be used totest the SM. The semiconductor die 106 may be configured (e.g., by thetesting hardware) to bypass faulty cores and/or SMs based on the testingthe semiconductor die 106. Further, the semiconductor die 106 may bematched to another component for inclusion in a face-to-face arrangementbased on the testing of the semiconductor die 106. For example, thesemiconductor die 106 and the semiconductor die 104 may each be testedand selected for inclusion in the face-to-face arrangement 102 based onthe number of cores and/or SMs that pass the testing (and/or otherperformance characteristics identified by the testing). This may be doneso that the composite semiconductor device collectively includes athreshold number of active cores or otherwise satisfies predeterminedperformance criteria.

Now referring to FIG. 5 , FIG. 5 is a flow diagram showing a method 500for testing at least one semiconductor die prior to assembly in aface-to-face arrangement with another semiconductor die, in accordancewith some embodiments of the present disclosure. The method 500 isdescribed using the semiconductor die 104 and the semiconductor die 106,by way of example only. Further, while the method 500 is described withthe semiconductor die 106 being tested, an instance of the method 500may additionally or alternatively be used with the semiconductor die 104being tested in place of the semiconductor die 106.

The method 500, at block B502, includes testing a first semiconductordie using probe pads formed on a face of the first semiconductor die.For example, testing equipment may test the semiconductor die 106 byprobing the probe pads 406 and 408 of FIG. 4A. In embodiments where thesemiconductor die 106 includes the testing tile structure 416 of FIG.4C, the probe pads 418 and 420 may also be probed to test thesemiconductor die 106.

The method 500, at block B504, includes forming at least an interfacelayer of the first semiconductor die over the probe pads. For example,after testing the semiconductor die 106, additional interface layers ofthe interface region 112 may be formed over the probe pads 406 and 408to result in FIG. 4B. As shown, the interface layers may include thebonding dielectric layer 152 and an inter-die interface pad layer(s)used to form inter-die interface pads such as the bump pads 154, 156,and 158.

The method 500, at block B506, includes mounting the first semiconductordie face-to-face with a second semiconductor die using the interfacelayer to couple at least one inter-die interface pad of the firstsemiconductor die to at least one inter-die interface pad of a secondsemiconductor die. For example, a pick and place machine may be used tomount the semiconductor die 106 to the semiconductor die 106 using thebonding dielectric layer 152 to couple the bump pads 154, 156, and 158to corresponding bump pads of the semiconductor die 104, as in FIGS. 1Band 3B. In other examples, the bonding dielectric layer 152 may not beused, such as where the inter-die interface pad layer is sufficient(e.g., the top surface of the semiconductor die 106 may be a singleinter-die interface pad). As described herein, the semiconductor die 106and the semiconductor die 104 may form at least part of a compositesemiconductor device, which may be tested through the backside of thesemiconductor die 106, the semiconductor die 104 (in embodiments whereprobe pads are included on the backside of the semiconductor die 104),and/or other semiconductor dies which may be in a stack with thosesemiconductor dies.

Thus, various approaches for enhancing semiconductor arrangements thatinclude face-to-face semiconductor dies have been provided herein. Theseapproaches may be mixed and matched in any suitable combination in orderto achieve semiconductor devices with desired characteristics.

As used herein, a recitation of “and/or” with respect to two or moreelements should be interpreted to mean only one element, or acombination of elements. For example, “element A, element B, and/orelement C” may include only element A, only element B, only element C,element A and element B, element A and element C, element B and elementC, or elements A, B, and C. In addition, “at least one of element A orelement B” may include at least one of element A, at least one ofelement B, or at least one of element A and at least one of element B.

The subject matter of the present disclosure is described withspecificity herein to meet statutory requirements. However, thedescription itself is not intended to limit the scope of thisdisclosure. Rather, the inventors have contemplated that the claimedsubject matter might also be embodied in other ways, to includedifferent steps or combinations of steps similar to the ones describedin this document, in conjunction with other present or futuretechnologies. Moreover, although the terms “step” and/or “block” may beused herein to connote different elements of methods employed, the termsshould not be interpreted as implying any particular order among orbetween various steps herein disclosed unless and except when the orderof individual steps is explicitly described.

The invention claimed is:
 1. A semiconductor device comprising: a firstsemiconductor die including, a semiconductor substrate, a first logiccircuit comprised in the semiconductor substrate, a layer of probe pads,a metallization region, and a layer of inter-die interface pads on afrontside of the first semiconductor die, and a second semiconductor dieincluding a semiconductor substrate comprising a second logic circuit;wherein a face-to-face arrangement includes the frontside of the firstsemiconductor die mounted to a frontside of the semiconductor die;wherein a layer of interface terminals of the first semiconductor die isconfigured as a first signal communications interface to the firstsemiconductor die and the second semiconductor die; wherein the layer ofprobe pads of the first semiconductor die is disposed between thesemiconductor substrate of the second semiconductor die and themetallization region of the first semiconductor die, the layer of probepads used to test the first logic circuit through the metallizationregion of the first semiconductor die prior to forming the face-to-facearrangement; and wherein the layer of inter-die interface pad layer isformed over the layer of probe pads and are configured as a secondsignal communications interface between the first logic circuit of thefirst semiconductor die and the second logic circuit of the secondsemiconductor die.
 2. The semiconductor device of claim 1, furthercomprising a layer of probe pads of the second semiconductor diedisposed between the semiconductor substrate of the first semiconductordie and the semiconductor substrate of the second semiconductor die andused to test the second logic circuit in the semiconductor substrate ofthe second semiconductor die through metallization layers of the secondsemiconductor die prior to forming the face-to-face arrangement.
 3. Thesemiconductor device of claim 1, wherein the probe pads of the layer ofprobe pads are parts of a plurality of testing tile structures disposedin a grid-like arrangement over the semiconductor substrate of the firstsemiconductor die and the plurality of testing tile structures surroundsa crossbar comprising the layer of inter-die interface pads.
 4. Thesemiconductor device of claim 3, wherein each testing tile structure ofthe plurality of testing tile structures respectively includesinterdigitated fingers of a redistribution layer, wherein a first probepad of the probe pads comprises a power terminal, a second probe pad ofthe probe pads comprises a ground terminal, and a third probe pad of theprobe pads comprises at least one signal terminal, and wherein the firstprobe pad, the second probe pad, and the third probe pad are eachelectrically connected to respective portions of the interdigitatedfingers of the redistribution layer.
 5. The semiconductor device ofclaim 1, wherein the layer of inter-die interface pad layer is a layerof bumps pads.
 6. The semiconductor device of claim 1, wherein the layerof inter-die interface terminals include microbumps electrically andmechanically connecting the first semiconductor die to an interposer andsolder bumps are electrically and mechanically connecting the interposerto a package substrate.
 7. The semiconductor device of claim 1, whereinthe layer of inter-die interface pads is formed on a backside probe padof the first semiconductor die using to test a composite logic circuitformed from the first semiconductor die and the second semiconductor diein the face-to-face arrangement.
 8. The semiconductor device of claim 1,wherein a signal path between the first logic circuit and the secondlogic circuit is internal to the first semiconductor die and the secondsemiconductor die and includes the first signal communicationsinterface, through substrate vias of the first semiconductor die,through substrate vias of the second semiconductor die, the secondsignal communications interface, a metallization layer of the firstsemiconductor die, and metallization layers of the second semiconductordie.
 9. The semiconductor device of claim 1, wherein the layer of probepads is formed over a top surface of a through substrate via of thefirst semiconductor die.
 10. A semiconductor device comprising: a firstsemiconductor die including, a first logic circuit, a semiconductorsubstrate, and a layer of interface terminals on a backside of the firstsemiconductor die; and a second semiconductor die including, asemiconductor substrate, a second logic circuit comprised in thesemiconductor substrate, a metallization region, a layer of inter-dieinterface pads on a frontside of the second semiconductor die, and aprobe pad layer; wherein a face-to-face arrangement includes a frontsideof the first semiconductor die mounted to the frontside of the secondsemiconductor die; wherein the layer of interface terminals of the firstsemiconductor die is configured as a first signal communicationsinterface to the first semiconductor die and the second semiconductordie; wherein the layer of probe pads of the second semiconductor die isdisposed between the metallization region of the second semiconductordie and the semiconductor substrate of the first semiconductor die, thelayer of probe pads is used to test the second logic circuit through atleast one metallization layer of the metallization region of the secondsemiconductor die prior to forming the face-to-face arrangement; andwherein the layer of inter-die interface pads is formed over the layerof probe pads and are configured as a second signal communicationsinterface between the first logic circuit of the first semiconductor dieand the second logic circuit of the second semiconductor die.
 11. Thesemiconductor device of claim 10, further comprising a layer of probepads of the first semiconductor die disposed between the semiconductorsubstrate of the first semiconductor die and the semiconductor substrateof the second semiconductor die used to test the first logic circuit inthe semiconductor substrate of the first semiconductor die through atleast one metallization layer of a plurality of metallization layers ofthe first semiconductor die prior to forming the face-to-facearrangement.
 12. The semiconductor device of claim 10, furthercomprising dielectric material disposed between the metallization regionand the layer of probe pads.
 13. The semiconductor device of claim 10,further comprising one or more vias formed in the layer of probe pads, avia of the one or more vias electrically and mechanically connecting alayer of the metallization region to an interface terminal in the layerof interface terminals.
 14. The semiconductor device of claim 10,wherein a probe pad of the layer of probe pads is configured to remainelectrically inert during operation of the semiconductor device.
 15. Thesemiconductor device of claim 10, wherein the layer of probe pads ispart of a plurality of testing structures and each testing structure isused to test a respective set of one or more cores of a processing unitformed in the semiconductor substrate of the second semiconductor die.16. A semiconductor package comprising: a first semiconductor dieincluding, a semiconductor substrate, a processing unit, a layer ofprobe pads, a metallization region, and a layer of inter-die interfacepads on a frontside of the first semiconductor die; a secondsemiconductor die including, a semiconductor substrate, and a processingunit; and package signal terminals to provide signals to a compositelogic circuit that includes the processing unit in the firstsemiconductor die and the processing unit in the second semiconductordie; wherein a face-to-face arrangement includes the frontside of thefirst semiconductor die mounted to a frontside of the secondsemiconductor die; wherein the layer of probe pads of the firstsemiconductor die is disposed between the metallization region of thefirst semiconductor die and the semiconductor substrate of the secondsemiconductor die, the layer of probe pads used to test the processingunit in the first semiconductor die prior to forming the face-to-facearrangement; and wherein the layer of inter-die interface pads is formedover the layer of probe pads of the first semiconductor die and areconfigured as a signal communications interface between the processingunit of the first semiconductor die and the processing unit of thesecond semiconductor die to form the composite logic circuit.
 17. Thesemiconductor package of claim 16, further comprising a layer ofinterface pads of the first semiconductor die, the layer of interfaceterminals being electrically connected to the package signal terminalsto provide the signals to the composite logic circuit.
 18. Thesemiconductor package of claim 16, further comprising a layer ofinterface terminals of the second semiconductor die, the layer ofinterface terminals being electrically connected to the package signalterminals to provide the signals to the composite logic circuit.
 19. Thesemiconductor package of claim 16, wherein the processing unit in thefirst semiconductor die is a first graphics processing unit (GPU) andthe processing unit in the second semiconductor die is a second GPU. 20.The semiconductor package of claim 16, wherein the layer of probe padsfurther includes one or more inductors formed from a same layer ofconductive material as the probe pads, and the one or more inductors areelectrically connected to one or more circuits of the composite logiccircuit.